package com.sky.interview;

import static java.lang.System.out;

import java.util.Random;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.ReentrantLock;

public class TestSyncMethods {

    public static void test(int round, int threadNum, CyclicBarrier cyclicBarrier) {
        new SyncTest("Sync", round, threadNum, cyclicBarrier).testTime();
        new LockTest("Lock", round, threadNum, cyclicBarrier).testTime();
        new AtomicTest("Atom", round, threadNum, cyclicBarrier).testTime();
    }

    public static void main(String args[]) {

        for (int i = 0; i < 5; i++) {
            int round = 100000 * (i + 1);
            int threadNum = 5 * (i + 1);
            CyclicBarrier cb = new CyclicBarrier(threadNum * 2 + 1);
            out.println("==========================");
            out.println("round:" + round + " thread:" + threadNum);
            test(round, threadNum, cb);

        }
    }
}

class SyncTest extends TestTemplate {
    public SyncTest(String _id, int _round, int _threadNum, CyclicBarrier _cb) {
        super(_id, _round, _threadNum, _cb);
    }

    @Override
    /**
     * synchronized关键字不在方法签名里面，所以不涉及重载问题
     */
    synchronized long getValue() {
        return super.countValue;
    }

    @Override
    synchronized void sumValue() {
        super.countValue += preInit[index++ % round];
    }
}


class LockTest extends TestTemplate {
    ReentrantLock lock = new ReentrantLock();

    public LockTest(String _id, int _round, int _threadNum, CyclicBarrier _cb) {
        super(_id, _round, _threadNum, _cb);
    }

    /**
     * synchronized关键字不在方法签名里面，所以不涉及重载问题
     */
    @Override
    long getValue() {
        try {
            lock.lock();
            return super.countValue;
        } finally {
            lock.unlock();
        }
    }

    @Override
    void sumValue() {
        try {
            lock.lock();
            super.countValue += preInit[index++ % round];
        } finally {
            lock.unlock();
        }
    }
}


class AtomicTest extends TestTemplate {
    public AtomicTest(String _id, int _round, int _threadNum, CyclicBarrier _cb) {
        super(_id, _round, _threadNum, _cb);
    }

    @Override
    /**
     * synchronized关键字不在方法签名里面，所以不涉及重载问题
     */
    long getValue() {
        return super.countValueAtmoic.get();
    }

    @Override
    void sumValue() {
        super.countValueAtmoic.addAndGet(super.preInit[indexAtomic.get() % round]);
    }
}

abstract class TestTemplate {
    private String id;
    protected int round;
    private int threadNum;
    protected long countValue;
    protected AtomicLong countValueAtmoic = new AtomicLong(0);
    protected int[] preInit;
    protected int index;
    protected AtomicInteger indexAtomic = new AtomicInteger(0);
    Random r = new Random(47);
    //任务栅栏，同批任务，先到达wait的任务挂起，一直等到全部任务到达制定的wait地点后，才能全部唤醒，继续执行
    private CyclicBarrier cb;

    public TestTemplate(String _id, int _round, int _threadNum, CyclicBarrier _cb) {
        this.id = _id;
        this.round = _round;
        this.threadNum = _threadNum;
        cb = _cb;
        preInit = new int[round];
        for (int i = 0; i < preInit.length; i++) {
            preInit[i] = r.nextInt(100);
        }
    }

    abstract void sumValue();

    /*
    * 对long的操作是非原子的，原子操作只针对32位
    * long是64位，底层操作的时候分2个32位读写，因此不是线程安全
    */
    abstract long getValue();

    public void testTime() {
        ExecutorService se = Executors.newCachedThreadPool();
        long start = System.nanoTime();
        //同时开启2*ThreadNum个数的读写线程
        for (int i = 0; i < threadNum; i++) {
            se.execute(new Runnable() {
                public void run() {
                    for (int i = 0; i < round; i++) {
                        sumValue();
                    }

                    //每个线程执行完同步方法后就等待
                    try {
                        cb.await();
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (BrokenBarrierException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }


                }
            });
            se.execute(new Runnable() {
                public void run() {

                    getValue();
                    try {
                        //每个线程执行完同步方法后就等待
                        cb.await();
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (BrokenBarrierException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }

                }
            });
        }

        try {
            //当前统计线程也wait,所以CyclicBarrier的初始值是threadNum*2+1
            cb.await();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (BrokenBarrierException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //所有线程执行完成之后，才会跑到这一步
        long duration = System.nanoTime() - start;
        out.println(id + " = " + duration);

    }

}